Strain-wave (harmonic) gear
Harmonic Drive CSG-2A component sets strain-wave (harmonic) gear
A high-torque version of the cup-type strain wave gear set. It carries more torque and lasts longer than CSF in the same size, with zero backlash.
Key specifications
| Rated torque (max) | 1,236 Nm |
|---|---|
| Peak torque (max) | 6,175 Nm |
| Speed (max) | 8,500 rpm |
| Ratio | 50–160:1 |
| Backlash (max) | 0 arcmin |
| Sizes | 14, 17, 20, 25, 32, 40, 45, 50, 58, 65 |
Summarised in our own words from Harmonic Drive SE / Harmonic Drive LLC's published data; series maxima, individual models vary. Last checked 2026-10-29. Source 1 · Source 2 · Source 3
Notes on this data
Torques are for CSG-65 (Harmonic Drive LLC table). Rated L10 is 1236 Nm, repeated peak 3419 Nm and momentary peak 6175 Nm. Size 14 starts at 7 Nm rated. Maximum input speed is 2800–8500 rpm depending on size, and power density is up to 545 Nm/kg (Harmonic Drive SE). Backlash is given only as 'zero backlash'. The CSG-2UH gear unit with output bearing has the same sizes and ratios.
Specify Motion is not affiliated with Harmonic Drive SE / Harmonic Drive LLC. Harmonic Drive and CSG-2A component sets are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Harmonic Drive CSG-2A component sets model codes
Published model codes in the CSG-2A component sets range, with key figures from the manufacturer's data. Search this page for your part number, or send it to us for availability or an equivalent.
| Model code | Size | Ratio | Repeated peak torque (Nm) | Momentary peak torque (Nm) |
|---|---|---|---|---|
| CSG-14-50-2A-R | 14 | 50 | 23 | 46 |
| CSG-14-80-2A-R | 14 | 80 | 30 | 61 |
| CSG-14-100-2A-R | 14 | 100 | 36 | 70 |
| CSG-17-50-2A-R | 17 | 50 | 44 | 91 |
| CSG-17-80-2A-R | 17 | 80 | 56 | 113 |
| CSG-17-100-2A-R | 17 | 100 | 70 | 143 |
| CSG-17-120-2A-R | 17 | 120 | 70 | 112 |
| CSG-20-50-2A-GR | 20 | 50 | 73 | 127 |
| CSG-20-80-2A-GR | 20 | 80 | 96 | 165 |
| CSG-20-100-2A-GR | 20 | 100 | 107 | 191 |
| CSG-20-120-2A-GR | 20 | 120 | 113 | 191 |
| CSG-20-160-2A-GR | 20 | 160 | 120 | 191 |
| CSG-25-50-2A-GR | 25 | 50 | 127 | 242 |
| CSG-25-80-2A-GR | 25 | 80 | 178 | 332 |
| CSG-25-100-2A-GR | 25 | 100 | 204 | 369 |
| CSG-25-120-2A-GR | 25 | 120 | 217 | 395 |
| CSG-25-160-2A-GR | 25 | 160 | 229 | 408 |
| CSG-32-50-2A-GR | 32 | 50 | 281 | 497 |
| CSG-32-80-2A-GR | 32 | 80 | 395 | 738 |
| CSG-32-100-2A-GR | 32 | 100 | 433 | 841 |
| CSG-32-120-2A-GR | 32 | 120 | 459 | 892 |
| CSG-32-160-2A-GR | 32 | 160 | 484 | 892 |
| CSG-40-50-2A-GR | 40 | 50 | 523 | 892 |
| CSG-40-80-2A-GR | 40 | 80 | 675 | 1270 |
| CSG-40-100-2A-GR | 40 | 100 | 738 | 1400 |
| CSG-40-120-2A-GR | 40 | 120 | 802 | 1530 |
| CSG-40-160-2A-GR | 40 | 160 | 841 | 1530 |
| CSG-45-50-2A-GR | 45 | 50 | 650 | 1235 |
| CSG-45-80-2A-GR | 45 | 80 | 918 | 1651 |
| CSG-45-100-2A-GR | 45 | 100 | 982 | 2041 |
| CSG-45-120-2A-GR | 45 | 120 | 1070 | 2288 |
| CSG-45-160-2A-GR | 45 | 160 | 1147 | 2483 |
| CSG-50-80-2A-GR | 50 | 80 | 1223 | 2418 |
| CSG-50-100-2A-GR | 50 | 100 | 1274 | 2678 |
| CSG-50-120-2A-GR | 50 | 120 | 1404 | 2678 |
| CSG-50-160-2A-GR | 50 | 160 | 1534 | 3185 |
| CSG-58-80-2A-GR | 58 | 80 | 1924 | 3185 |
| CSG-58-100-2A-GR | 58 | 100 | 2067 | 4134 |
| CSG-58-120-2A-GR | 58 | 120 | 2236 | 4329 |
| CSG-58-160-2A-GR | 58 | 160 | 2392 | 4459 |
| CSG-65-80-2A-GR | 65 | 80 | 2743 | 4836 |
| CSG-65-100-2A-GR | 65 | 100 | 2990 | 6175 |
| CSG-65-120-2A-GR | 65 | 120 | 3263 | 6175 |
| CSG-65-160-2A-GR | 65 | 160 | 3419 | 6175 |
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with a Harmonic Drive part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These 3 series from our supply network are the closest match on published figures.
Cup-type strain-wave gear component sets for building your own joint; the LCSG high-torque version lifts capacity by around 30% over the standard LCS.
| Published maximum | CSG-2A component sets | LCS / LCSG |
|---|---|---|
| Rated torque | 1,236 Nm | — |
| Peak torque | 6,175 Nm | — |
| Ratio (max) | 160:1 | 500:1 meets or exceeds |
| Backlash (lower is better) | 0 arcmin | — |
Hollow-shaft strain-wave gear units with a large central bore for routing cables and services; LHSG is the high-torque version (over 30% more torque).
| Published maximum | CSG-2A component sets | LHS / LHSG |
|---|---|---|
| Rated torque | 1,236 Nm | — |
| Peak torque | 6,175 Nm | — |
| Ratio (max) | 160:1 | 500:1 meets or exceeds |
| Backlash (lower is better) | 0 arcmin | — |
Ultra-flat cup-type strain-wave gear with a very short axial length, light weight and high stiffness for its size.
| Published maximum | CSG-2A component sets | LCD |
|---|---|---|
| Rated torque | 1,236 Nm | — |
| Peak torque | 6,175 Nm | — |
| Ratio (max) | 160:1 | 500:1 meets or exceeds |
| Backlash (lower is better) | 0 arcmin | — |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What a strain-wave (harmonic) gear is
A strain-wave gear, often called a harmonic gear, reduces speed using three parts: an elliptical wave generator, a thin flexible toothed cup or hat called the flexspline, and a rigid circular spline with internal teeth. The wave generator deforms the flexspline so its teeth engage the circular spline at two points. Because the flexspline has typically two fewer teeth, each input turn advances it slightly, giving ratios of about 30:1 to 160:1 in one stage, with near-zero backlash.
When engineers choose a strain-wave (harmonic) gear
Choose a strain-wave gear for compact, lightweight, high-ratio reduction with near-zero backlash, such as robot joints, cobots, medical robots, aerospace and optics. Hollow versions allow cables through the centre. The trade-offs are torsional stiffness at low load, which is lower than some alternatives, limited input speed and the risk of tooth ratcheting under overload. For shock loads and heavy base joints, cycloidal reducers are often preferred.
How to specify the Harmonic Drive CSG-2A component sets
Send these with your enquiry and an engineer can confirm the right CSG-2A component sets variant or an equivalent:
- Ratio (:1)
- Rated, peak and momentary torque (Nm)
- Input speed limits (rpm)
- Torsional stiffness (Nm/arcmin)
- Hysteresis and accuracy (arcmin)
- Component set or housed unit
- Hollow shaft diameter and output bearing loads
Common mistakes to avoid
- Exceeding momentary torque and ratcheting the teeth
- Ignoring low-load stiffness in precision control
- Poor housing tolerances for component sets
- Using the wrong lubricant or quantity
Harmonic Drive CSG-2A component sets: frequently asked questions
What is the Harmonic Drive CSG-2A component sets?
A high-torque version of the cup-type strain wave gear set. It carries more torque and lasts longer than CSF in the same size, with zero backlash. Published series figures include rated torque 1,236 Nm, peak torque 6,175 Nm, speed 8,500 rpm, ratio 50:1. It is made by Harmonic Drive SE / Harmonic Drive LLC; Specify Motion can help source it or propose an equivalent.
Who makes the Harmonic Drive CSG-2A component sets?
The Harmonic Drive CSG-2A component sets is made by Harmonic Drive (Harmonic Drive SE / Harmonic Drive LLC) and is listed here for engineers comparing options. Specify Motion is not affiliated with Harmonic Drive SE / Harmonic Drive LLC; brand names are used only to identify the product.
What model codes are in the Harmonic Drive CSG-2A component sets range?
The CSG-2A component sets range includes CSG-14-50-2A-R, CSG-14-80-2A-R, CSG-14-100-2A-R, CSG-17-50-2A-R, CSG-17-80-2A-R, CSG-17-100-2A-R, CSG-17-120-2A-R, CSG-20-50-2A-GR and 36 more. The table on this page lists each published model code with its key figures. Send us the code you use, or the one you need to replace, and our engineers will confirm availability, lead time or the closest equivalent.
What is the rated torque of the Harmonic Drive CSG-2A component sets?
The published series maximum rated torque is 1,236 Nm. Individual models and sizes in the CSG-2A component sets range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the Harmonic Drive CSG-2A component sets?
Yes. On published figures, LeaderDrive LCS / LCSG and LeaderDrive LHS / LHSG are the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
Why do strain-wave gears have near-zero backlash?
The flexspline teeth are preloaded into the circular spline teeth by the elliptical wave generator, and many teeth engage at once. There is no clearance between teeth at the engagement zones, so backlash is close to zero. Lost motion comes mainly from elastic deflection.
What is the difference between a strain-wave component set and a housed unit?
A component set is the wave generator, flexspline and circular spline, which the machine builder mounts in its own housing with bearings. A housed unit adds a housing, output bearing and seals. Component sets save weight and space; housed units are easier to integrate.
Further reading: Harmonic vs planetary vs cycloidal · How to select a gearbox · Gearboxes and harmonic drives
Other strain-wave (harmonic) gear series
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